 Dear students, in this topic we shall discuss the costs and benefits of ectothermia. The ectotherms have certain advantages and disadvantages as compared to the endotherms. Being an ectotherm has its biological costs and benefits which are inverse to those of being an endotherm. We can make certain generalizations about the costs and benefits of both groups, ectotherms and endotherms. First we shall discuss the benefits of ectothermia and compare it with those of endothermia. The first benefit of ectothermia is that ectotherms use less energy in maintaining metabolic rate and temperature. So they can conserve a lot of energy over 50% which can be used in more important functions that is growth and reproduction. In comparison, endotherms utilize about 98% of their energy in maintaining their metabolic rate and body temperature. The second benefit of ectothermia is that they require less food. The advantage of ectothermia is that they require less time in the process of obtaining food that is foraging. Endotherms are big consumers so they spend more time on foraging. For example, a lizard or a rodent who live in the same habitat or take the same diet, then if we compare them with a lizard that takes 17 times less food than the rodent. Dear students, the third benefit of ectothermia is that the ectotherms which live in comparatively cooler microclimates or habitats, they face less evaporative water loss. Since they do not have a lot of water loss that is why they have not massive bodies to reduce the surface area to volume ratio. In comparison, the endotherms are more evaporative water loss or they lose water from other mechanisms as well so they are comparatively massive and bulky to reduce their surface area to volume ratios. Low respiratory rates in ectotherms also reduce water loss that also gives them the same benefit. Dear students, ectotherms are the most successful animals in the environment. They even out compete endotherms in those environments. First of all, reptiles' population and diversity in the number of species is much more than reptiles' in the tropics. This competitive success is due to their greater energy economy. Dear students, apart from the benefits, there are some disadvantages or costs of ectotherm. Number one, ectotherms require behavioral thermoregulatory activities. These activities are always time consuming and also have certain limits. For example, basking in the sun, that is time wasting as well as limiting that if solar radiation is not available then they cannot warm up their bodies. Number two, ectotherms generate and expand lower energy. Due to this, they cannot sustain longer periods of intense activity. The third disadvantage of ectothermy is that the constancy of body temperature lowers the activity of their enzymes. Their enzymes become intermittently active. The endotherms work efficiently without fluctuation. The disadvantage of ectothermy is that ectotherms are comparatively sluggish animals and they are less competent in cold climates. That is why ectotherms of this type of predator type are less competent in temperate regions and cold climates. Endotherms have a significant competitive edge over ectotherms in cold climates. The fifth disadvantage or cost of ectothermy is that they are often less active. Due to their lower activity, they are more vulnerable to predation. If they are staying in the sun or they have gone to long sleep due to their temperature falling then in that case they are more vulnerable that they are more likely to die. That is why their survival is in danger because of ectothermy.